To perform cell biology, neuroscience and physiology experiments realistically a relevant temperature must be used and maintained for the duration of experimental measurements. Imaging and microscopy methods are used extensively in the lab that I work in and for temperature regulation we chose products from Harvard Apparatus. Rather than choosing pre-existing cell chambers however, we use temperature controllers and micro-incubators from Harvard Apparatus and have custom ‘inserts’ fabricated by the excellent Physiology machine shop here at UCSF to fit the incubator. This method gives us flexibility and also means that the micro-incubator can be adapted to multiple uses.
The temperature controller we use is the TC-202A which heats or cools cell chambers (as such it is a bipolar – heats and cools- as opposed to a monopolar unit). This controller can be used in conjunction with multiple micro-incubators such as Peltier-based incubators (including the PDMI-2 from Harvard that we use extensively) or incubators that rely on resistive heaters. The controller is relatively large (at ~20 x 4 x 14 inches) and heavy, although we manage to store the units conveniently on shelving above our microscopes. The TC-202A temperature controller is characterized by a large range of operating temperatures, excellent thermal regulation (± 0.2 °C) and low electrical noise, which could interfere with electrophysiological measurements. Finally, the display on the unit is large and easy to read and temperature can be monitored either at the connected micro-incubator or remotely with a separate thermistor.
The second part of the system is the incubator and we ‘adapt’ the PDMI-2 Open Perfusion Peltier micro-incubator to our requirements. As the name suggests, this incubator was designed for use in an open configuration for e.g. electrophysiological measurements using electrodes. To increase the flexibility of this incubator we have had a series of stainless steel inserts machined to fit this unit. We can thus use the system for microscopy/imaging of tissue samples with an open chamber and we also have chambers designed for cell cultures (grown and mounted on 18 mm glass cover-slips) that are used for microscopy/biophysical experiments on upright and inverted microscopes. Although we have chosen to use custom fabricated cell/tissue chambers Harvard Apparatus do supply inserts that may satisfy your experimental requirements. The micro-incubator itself is relative small (~6 inch diameter) but sturdy such that it sits ‘firmly’ on a microscope stage. The incubator also has provision for inline solution warming if continuous perfusion is used although we tend to use static conditions with pre-warmed solution.
Together, the temperature controller, micro-incubator and cell/tissue inserts yield an excellent system for temperature regulation. We have multiple units in the lab and this is testament to satisfaction from both experimentalists and the PI. Further, we have had relatively few problems with the systems indicating their reliability. Together, the temperature controller and micro-incubator cost ~$5000. There maybe cheaper solutions to temperature regulation but the Harvard Apparatus system is reliable and robust.
Peter Haggie, Ph.D.
Post-Doctoral Fellow
University of California, San Francisco